1. What is needed to make a bulb light?
Hypothesis: Based on previous dealings with batteries to get the light to work it will need a bulb in a socket, battery, and 2 wires connected to battery.
2. What will happen to Bulbs 1 and 2 when you disconnect the wires of the configuration below at the various labeled points?
Hypothesis: At each of the points where the wire is disconnected, lights will not stay on because it is no longer a complete circuit.
Conclusion: Based on the results the lights are not on, the light does not get the electron flow from a closed circuit. This does not allow electrons to flow.
3.What type of object, when inserted into the space labeled “something” in the loop shown below, will allow the bulbs to light?
Hypothesis:
Conclusion: My hypothesis was accurate. All the materials above that did work were metallic, while all those that did not work were, the non metallic materials. The metallic are the conductors and the non metallic are the insulators. The conductors will close the circuit while the insulators do not keep the circuit working.
4. What is a conductor and what is an insulator? How do you know? How can you test this using our loop configuration?
A conductor allows for the flow of electrons, while an insulator does not. I know this because of the last investigation. I made an open circuit, leaving a space open between two wires, one connected to the socket and the other connected to the positive end of the battery. On the negative end, one end of the wire was connected to the battery and the other to the socket. I then connected the two open end of the wires with various objects. Some things were metal while others were not. In the end, the metal objects such as a paper clip and piece of tin foil lighted the bulb.
5. What parts of a socket and bulb are conductors and which are insulators? What is the conducting path through the bulb?
Hypothesis: The clips and the plates on the socket and the threaded section and the tip on the bulb will be conductors. From feel and look they seem to be metal, which is a conductor. Because of the previous data the base on the socket and the black ring and the glass on the bulb will be insulators. The conducting path will run through the fixed metal strips on the blue plastic disc in order for the power to reach the light bulb.
Procedure: Set up a complete circuit, disconnect one wire from the bulb socket. Touch the open wire end to the parts of the socket and see which ones allow the bulb to light. Test out the parts of the bulb.
Conclusion: My hypothesis was accurate. In the socket, the clips and plates were conductors. In the bulb, the threaded section, filament, and tip were conductors and allowed light. Below is the conclusion on the path throughout the bulb and socket.
6. Practice Set: The CCP
Sheet 1
Sheet 2
7. How can you light a bulb using one battery, one bulb, and one wire ONLY? How many different correct ways can you do this? What DIDN’T work, and why?
Hypothesis: To get the bulb to light I will need to touch one end of the wire to one side of the battery and the other to the thread of the bulb while touching the tip to to the positive side of the battery if the negative side is being touched by the other wire. This can be done through two ways.
Conclusion: My hypothesis was pretty correct but there will be four total ways instead of two. Both work with the bulb on positive or negative end instead of just on one. For the bulb to light using the battery, wire, and bulb, both the threaded section and the metal tip must be connected to either the battery or a wire that is connected to the battery. Those two pieces of the light bulb need to be connected to a source of power. There will be no light if either the threaded section or metal tip is not touching a source of power.
8. Practice Set: Basic Circuits
1. in the Following circuit which bulb lights first?
Answer: D they all light the same.
9. What is a circuit?
A circuit is a closed loop of conducting materials that allows electricity to flow freely.
10. What does a compass tell you about what is happening in the wires of the circuit?
Hypothesis: The compass needle will move when the wire is placed directly on top of it.
Procedure:
Data: When wire is placed in same direction of needle, the needle attempts to move perpendicular to the wire.
Conclusion: The needle attempts to move perpendicularly with the electricity flow. The needle will be deflected more with a stronger electricity flow. It deflects in the same direction when touched with the same end of a wire.
11. What effect does reversing the battery pack have on the compass deflection? What does this mean about the role of the battery in the circuit?
Hypothesis: The needle will move in the opposite direction compared to the investigation 10.
Procedure: Set up the same way as previous investigation and switch the two wires connected to the battery and observe what happens.
Data: The needle will move the opposite way compared to the data in investigation 10.
Conclusion: Whichever side the wire is plugged in to defines the path of the electrical flow
12. Practice Set: Wires 2. Explain why you believe your answer to Question #3 is correct. Use the words “insulator” and “conductor” correctly as part of your explanation.
Since the paperclip is a conductor, they both will have the same brightness because the same amount of charge will pass throughout the circuit. If it was an insulator, there would be no light to the bulbs.
3. Write in your own words a definition of the word circuit which anyone could use to determine if a given set of connections is or is not a circuit. It is a closed loop of conducting objects. They allow a current to flow through.
4. We have observed in several activities that as soon as a very small gap is produced anywhere in the circuit, the bulbs go out. Would you classify air as a conductor or an insulator? Explain. Air is an insulator because electric charges cannot be moved through it. In the cases of high voltage like lightning, air can act as a conductor.
5. Indicate whether each of the following statements is True or False. Then state evidence which either supports or contradicts each statement.
False [a] Charge moves out of each end of the battery into the loop. Evidence: A compass needle deflects the same way no matter where it is in a loop.
True [b] Light bulbs are non-directional devices. (Whichever way they are connected in the circuit, they behave the same way if you turn them around.)
Evidence: Whatever way a bulb is connected to a circuit, it will have the same reaction. There is a continuous conducting path within the circuit.
True [c] The battery determines the direction of flow of charge in a circuit.
Evidence: The compass needle deflects the opposite way.
False [d] A compass can be used to determine the exact direction that charge flows in a circuit.
Evidence: We do not know the exact direction the charge flows, but the scientific community accepts that it flows from positive to negative.
True [e] Metal substances are generally conductors.
Evidence: Determined from previous investigations placing a metallic substance in the circuit keeps the light lit which means it is a conductor, so they complete the circuit.
13. What is a Genecon and how does it work? What does it tell you about the role of the battery in the circuit and why?
Hypothesis: A Genecon is power source which will effectively take the place of the battery in the circuit.
When cranked connected to a bulb, at a certain speed the bulb, lights.
The crank begins to turn when plugged into the battery. The circuit is completed when the power runs through the motor of the Genecon.
Conclusion: A Genecon is a manual-powered generator. The crank initiates the power, energy is transferred to the gears which move the motor. The power transferred into the motor then transfers electricity to the wires.
14. Readings
15. What is a schematic diagram? What are the symbols for the various circuit elements?
Schematic diagrams represent the components of a circuit through symbols. Schematic diagrams are an easier, more clear way to represent real-life circuits.
16. Practice Set: Schematics
17. Readings: Capacitance
18. What is a capacitor and how is it made?
A capacitor is a three layer device that is used to store certain amounts of charge and energy. It is made by putting an insulator layer (dielectric layer) in between two conducting layers (plates). These layers are rolled up and put inside a cylinder. The plates are made very thin and each has a screw or wire called a terminal, attached to it so it can be connected to a circuit.
19. What is the effect of a capacitor on a closed loop?
Hypothesis: Circuit A will not light unless there is charge already stored in the capacitor. Circuit B will light once the wire are reset, which occurs when they touch each other after being connected to the circuit.
Procedure:
Conclusion: A capacitor is a device used to store energy though a connection to a power source. They eventually stop flow of charge.
20. What is origin of mobile charge? From where does the mobile charge originate during the charging and discharging process?
Hypothesis: Charging circuit- the mobile charge will originate from the batteries. Discharging circuit- the mobile charge will originate from the charge stored in the capacitor.
Procedure: Set up a circuit like the ones below. Which are represented by symbols from schematics, so you need three batteries, a capacitor, and two bulbs with sockets.
Conclusion: Mobile charge originates from where the circuit begins its positive charge that flow.During the charging process, mobile charge originates front the conductors in the circuit. The charges are pushed by the battery to the first terminal. During the discharging process, mobile charge comes from the built- up positive charge in one terminal. The charge then repels the positive charge in the other terminal and pushes it through the circuit.
21. Practice Set: Electrical Energy
22. Make a model: Air Capacitor
23. Investigating the Air Capacitor
24. Practice Set: Capacitance
Part 2: Resistance
1. What effect does the type of bulb have on a capacitor during charging and discharging?
Hypothesis: Discharging through the long bulbs will take longer for the long bulbs to go out compared to the round bulbs because of the long's thinner filament. As for the genecon, during the discharge process, the built up charge in the capacitor will cause the genecon to crank because the charge will be running through it.
Procedure:
Conclusion:
Upon switching off between the long bulbs and the round bulbs during the discharge process after charging with the round, I was able to see that the long bulbs stayed on for a longer amount of time in comparison to the round which lastly a bit shorter. During the discharging process of the capacitor, when connected with a genecon, it will cause the genecon's handle to twist in counterclockwise direction. Showing the charge moving away from the capacitor.
2. What are the differences between the filaments of round and long bulbs? (Use a microscope.)
The Filament of the round bulb is thicker and smaller in relation to a long bulb, whereas the filament of the long bulb is thinner and longer.
3. How is air moving through straws analogous to charge moving through a filament? Air moving through straws is analogous to charge moving through a filament. Breathing through a thick straw is easier and quicker in comparison to a thin straw, which takes longer and is more difficult to breath through. This analogy fits well because it very similar to how charge moves through filaments. With a thin filament, there is a longer time for charge to pass throughout compared to a thicker one. In the thick one, it the charge moves through quicker. Shorter straws were easier to breathe through compared the longer ones. Charge takes longer moving through a longer filament compared to a shorter filament.
4. What is the difference between flow rate and flow speed?
Flow rate is current and how many charges per second. Flow speed is the amount of distance you cover in an amount of time.
5. How does the number of bulbs in a single loop affect the overall current and resistance in a circuit?
Hypothesis: As the number of bulbs increase, the amount of resistance increase, which will slow down current. This will cause the brightness of the bulbs to decrease as the amount of bulbs increase.
Procedure:
Data:
Conclusion: The more bulbs there are the higher the resistance, so the brightness ultimately decreased as more bulbs were added to the circuit. Also, the amount of deflection in the compass also decreased because the current had decreased. That is the charge passing over a given point per amount of time. So, as the the resistance is increased the current will decrease because the charge is moving slower throughout the circuit.
6. Problem Set: Resistance
8. Reading and Questions: Pressure Difference
9. and 10. Color Coding Notes, Activity and Practice Set
11. How does the number of bulbs side-by-side affect the overall current and resistance in a circuit?
Hypothesis: Adding light bulbs will not affect the overall current or resistance. There will be an equal amount of charge flowing through each bulb after the current reaches the junction.
Procedure:
Data:
Conclusion: The number of bulbs in a side by side does not affect the current in these circuits. I was able to se this because the compass deflected the same amount throughout each set up. Resistance stayed the same throughout each circuit. It does not lower the resistance, exemplified by the fact the bulbs were the same brightness. When there are parallel wires all the bulbs light the same.
12. Does adding wires in series or in parallel effect the overall resistance of the circuit?
Hypothesis: Adding wires into a series will not affect the overall resistance because the wires have very little to no resistance. Adding wire in parallel will decrease the overall resistance in a circuit, because it will create a path of less resistance for the charge, essentially one that is easier to move through.
Procedure:
Data:
Conclusion: Adding a wire in series does not affect the overall resistance of the circuit. This is because the wires used nearly have no resistance. When wires are placed parallel into a circuit, it will affect the overall resistance, decreasing it. Since charge wants to move through the path that is least resistant, the one bulb in the circuit will be short-circuited because it is easier for the charge to move through wire than through the bulb. Evidenced by deflection of the compass, as the current increased total resistance decreased.
13. What effect do dueling battery packs have on bulb lighting and flow rate?
Hypothesis: Dueling battery packs will have resistance within a series facing opposite directions but combined voltage when facing the same, but no effect when parallel.
Procedure:
Data:
Conclusion: Adding batteries in a series will add or subtract from the total charge moving throughout the circuit. This is because the batteries themselves have resistance within the circuit.
14. Practice Set: Battery Structure
15. How does mixing bulbs in series affect flow rate and pressure in each part of the circuit?
Hypothesis: Mixing Bulbs in a series will affect the flow rate making the circuit flow at the resistance of the most resistant light bulb which is the long bulb. The long bulb will light while the round bulb will not. When the capacitor is added, the long bulb will not light at first and the round bulb will be lit but as the resistor builds resistance, the round bulb will begin to go out while the long bulb's brightness will increase.
Procedure:
Conclusion: Mixing bulbs in a series will cause a change in the flow rate and the resistance throughout the circuit. The flow rate depends directly on the most resistant object in the circuit. The circuit will flow at the rate of the long bulb so the round bulb is not lit. When a capacitor is added, it short circuits the long bulb when it begins to charge. The round bulb will be lit brightly because the long bulb is short-circuited but as the capacitor gains charge the long bulb will gain brightness as the round bulb loses brightness.
16. Reading: Mixing Bulbs
Immediately after connection:
Mid-way through the process:
Steady State:
17. What is the effect of adding another round bulb in parallel?
Hypothesis: Adding another bulb in parallel will increase flow rate and cause the bulbs in the series to get brighter.
Procedure:
Data: When the additional bulb is added, the bulbs in a series get brighter, while the parallel bulbs have the same brightness and do not change from what it was previously.
Conclusion: When adding another round bulb in parallel, the flow rate increases. The parallel bulbs let the charge flow through two different paths, which decreases the resistance of the circuit. This results in the two outer bulbs getting brighter and the two parallel bulbs getting dimmer. The two bulbs in series get brighter because the current increases. The two parallel bulbs do not get brighter because the current splits when it is going to the two bulbs.
18. How does the addition of another branch affect flow rate and pressure in the wires?
Hypothesis: By adding another round bulb parallel it will increase flow rate. (we can see this with a compass deflecting more) Circuit 3 will have the highest flow rate and thus the most deflection on the compass. This is because the long bulb shorts out by the parallel wire. The circuit will have low resistance because the highest resistance will be the round bulb which has low resistance.
Procedure:
Data: The compass deflects more when there is less resistance in the circuit. The compass deflected the most when a wire was added. Then when the round bulb was added it deflected a little bit less. Finally when the long bulb was added, the deflection on the compass was the least. With less resistance, the bulbs became brighter.
Conclusion: Adding another branch increases the flow rate because of the amount of compass deflection in the three circuits. For circuit 1 and 2, the pressure was the same. In circuit 3, the pressure increased because the parallel wire shorts the long bulb. Because another option for the charge to flow through is added, the current will increase.
19. What is the effect of decreasing the resistance of right side of the circuit on: a) the flow rate through the battery; b) the pressure difference across the battery; c) brightness of the left bulb
Hypothesis: By adding round bulbs to the right of the circuit, the flow rate will increase. The pressure difference will not be affected so the long bulb on the left will keep a consistent brightness.
Procedure:
Data:
Conclusion: Upon decreasing the resistance of the circuit, it will increase flow rate through the battery, and keep the pressure difference and brightness of the left bulb constant. The flow rate increases because less resistance is added to the right, which is shown through the increased deflection in the compass. The pressure difference remains constant. The long bulb has the same brightness because the pressure difference remains constant and it is not affected by the addition of a parallel branch to the battery.
20. Practice Set: What determines Pressure in the Wires?
21. Activity/ Lab Ammeter Voltmeter
Objective: How do different bulb combinations and arrangements affect the quantitative and Voltage and Current Readings?
Procedure: Set Up each of circuits below, and measure pressure difference with a voltmeter and flow rate with an ammeter.
Hypothesis:
A. Predict the bulb brightness and flow rate, showing this with starbursts and arrow tails.
B. Rank each of the circuits in terms of flow rate through the battery
(Least to Greatest) H, G, B, F, D, C, A, E
Data:
Pressure Difference Units are V
Flow Rate Units are A for circuits A, E, and H and milliA for B, C, D, F, and G
When bulbs are in parallel, the voltage throughout the circuit remains constant. The current splits after the junction and add up to the total current at points A and D which are right before and after the battery.
When bulbs are in series, the total voltage throughout the circuit adds up to the voltage in a battery. The current remains the same throughout the circuit in a series.
Discussion Questions:
Conclusion: Quantitatively current and voltage have different readings when working with circuits and in parallel and in series. In parallel, the voltage will all be equal. The currents will add up to the total current of the power source. In a series the currents will all be equal. The voltage will add up to the total voltage of the power source.
22. True/ False Statements
Part 3: Quantitative Analysis of Electrical Circuits
2. Summary of Lesson 2 (Electric Current) on Electric Circuits - Method 4
What is an electric current? Electric current is a flow of electric charge. It is moving electrons in a conductor. Charge moves from an area of high potential to low potential.
What are the requirements of a circuit? Must be a closed loop. Must have an energy supplies with high and low potential ends. Must consist of all conducting materials
How do you measure electric current? As a physical quantity, current is the rate at which charge flows past a point on a circuit. Current is I, and is equal to the quantity charge that passes through a point per amount of time. Current is measured using amperes, which is 1 coulomb / 1 second
What is power (in electrical terms)? Power is the rate at which electrical energy is supplied to a circuit or consumed by a load. A cell does work upon a charge to move it from the negative to the positive side of itself. The work done on the charge is equivalent to the electrical potential energy change on the charge. The electrical power is the rate at which work is done. Power is defined as such: Power is measured using watts, which is joules per second.
What is a common misconception regarding electric circuits? Batteries are not rechargeable. They die when they lose a significant potential difference between their two terminals.
Circuit need to be completely closed in order to actually have a current. This leads to electric charges flowing throughout the circuit, with the battery supplying the power for the whole circuit. People have misconceptions about how this works, in reality, battery just allows the difference in voltage to start the flows and wear out when the voltage dwindles from resistance.
4. Read and Summarize Lesson 3
What is the journey of a typical electron? Electrons carry charge. It will move from high potential to low. It collides with many atoms of the conducting wire, which causes a loss of energy
What is resistance? Resistance lessens the flow of charge. Flow rate is the result of how much resistance is present. The longer the wire the more resistance there is. Materials of the conductor affect resistance as well.
What is Ohm's Law? The equation of Ohm's Law is V=IR. This can calculate current, voltage, and resistance of parts of a circuit. There are such things known as Ohmic material which means that it follows this equation. Non-Ohmic material doesn't follow this equation and has a resistance that is constantly changing depending on the situation.
How does Power fit in with Electrical Resistance? Electrical power is the rate at which electrical energy is supplied to a circuit or consumed by a load. The equation for calculating power is P=VI. P=RI2 and P=V2/R.
6. Ohm's Law Lab
10/28/11
Purpose: We are trying to find the relationship between pressure difference and flow rate. We are also trying to find the difference between ohmic and non-ohmic materials.
Hypothesis: The relationship between potential difference and current is direct with constant resistance because when increasing voltage by adding batteries to a circuit, the bulbs became brighter showing an increase in current. (known from previous investigations)
Procedure:
Materials- variable power supply, batteries/ holders, long bulb and socket, assorted resistors, multimeters, lead wires
1. Set up the above circuit.
2. For the resistor, use 4 different resistors, two different normal resistors, a long bulb, and round bulb.
3. Change the voltage of the circuit at least 5 times when each resistor is completing the circuit. Use the ammeter to determine the current.
4. Record both the voltage and current in excel for each different voltage and resistor.
Calculations:
Resistance Calculation:
Percent Error Calculation:
Percent Difference Calculation:
Graphs:
Analysis: We started the graphs at 0,0 because when there is no electric potential there is no current. The two resistors we used had linear tread lines. This shows that they follow ohm's law, so they are ohmic resistors.The slope of the line is equal to the electric potential divided by the current. The slope is the resistance, known from Ohm's law where v/i=r. The slope should be equal to the experimental resistance. The tread lines for the round and long bulbs were polynomial (supposed to be power but did not work on our excel sheet). This shows that they were non ohmic resistors. We are able to determine that these tread lines were correct fits for each particular data set because they all had strong R^2 values which determine the fit and accuracy of the line.
Discussion Questions:
Conclusion:
My hypothesis that there is a direct relationship between electric potential and current was correct. We were able to see this graphically upon graphing the data that we recorded from our procedure. On the graphs, as the x value increase, the y value increases, showing a direct relationship. Since we were looking for a direct relationship, we know that when current increases, the electric potential must increase also, so quantitatively we are able to see that this proven true. In our data, the current is at .0128 A when the electric pressure is at .200V, so when the current increases to .0223 A we see that there is an increase in electric pressure to .400V. Looking at the graphs we can determine difference between ohmic and non-ohmic materials. The resistors tread lines that were linear, compared to the bulbs had tread lines, which were power fits. The linear fit equation is the equation from Ohm’s law where v/i= R. The power fit shows there is an exponential relationship on the tread lines of the bulbs, which have determined that they are non-ohmic. They do not follow Ohm’s law because the x value is squared.
Our error was pretty high in compared to our results because our predicted error on the resistors was 5% with a predicted resistance of 22 ohms and 150 ohms. Our experimental error was around 15%, which is much more, then what we had expected. The average resistances we had were 18.18 ohms and 123.76 ohms. Our long bulb and round bulb results had high percent errors at 60 % with an average of 13.7 ohms instead of 60 ohms for the long and 50% with an average 4.69 ohms instead of 10 ohms for the round. This should have been much less, closer to 5-10%. There is a possible error within the bulbs and resistors because they have been used a lot previously. They could have experienced a lot of work and were not as fresh as new bulbs would have been. So to fix it, we should use brand new bulbs and resistors next time. Also there could have been a problem with the manufacturing. Since the bulbs are mass-produced there could have been a problem from the get go. Once again we should just use brand new bulbs.
There are real-life applications within this lab, which can be applied to circuit boards and electronics. It can help to use a resistor to prevent too much voltage flowing through the circuit. The resistor can prevent too much current in the circuit also.
Lab: Kirchoff's Rules 11/3/11
Purpose: We are looking to see how current splits in multi-loop circuits.
Hypothesis: The sum of the current in the branches will equal the current of the power supply because current splits in parallel circuits. The most current will flow through the path of least resistance, because as we have investigated charge wants to flow through the least resistant parts of a circuit.
Procedure:
Materials: Resistors, Wire Leads, D- cell batteries, Several digital mutimeters (DMM), 2 power supplies, 3-4 resistors, connecting wires
1. Set Up the following 4 circuits
A
B
C
D
2. Draw a schematic diagram for each.
3. Measure current and voltage in all resistors using an ammeter and voltmeter. (Use as Experimental Values)
4. Calculate current and voltage in all resistors. Use as Theoretical value and calculate the percent error compared to the experimental
Sample Calculations:
Circuit A
Circuit B
Circuit C
Circuit D
Analysis: (The percent error for I, V, andR is highlighted in yellow at the far right of the table)
Discussion Questions:
Conclusion:
My hypothesis was correct. When current splits it they will add up to the current flowing out of the battery and the most current will flow through the path of least resistance. From our data and calculations we can see in circuit C where there is .0096A flowing out of the battery. The circuits of each branch are .0006A, .0080A, and .0010A. When all are adding up they equal the total flow out of the main battery. An example of the most current flowing the branch will the least resistance will be circuit B. where resistor 1 had a resistance of 500 ohms in one branch, and resistor 2 in branch 2 has 1000 ohms. Resistor 1 has .00078A of current and Resistor 2 has .00063A. Since Resistor 1 has less resistance, it has the most current.
Our results of this lab were pretty good demonstrated by the fact we did not have a lot of error. Our error was around the 5% error for most of the current and voltage, but there was an outlier. Resistor 1 in Circuit D had a 15.66% error for I and 23.5% error for V. Although it was not a large amount of error it still can be attributed to the fact we did not take in account the amount of resistance from the ammeter and wires. If we had taken those into account the error could have been slightly lower. Since the resistors resistances are not exact, they could have been the problem. Depending on which one being used, some contain error ranging from 5-20%. Because of this we could have had a resistor with a not so exact resistance, which we did not incorporate into our calculations.
In the future, I would make sure to check the resistors and see their range and try to use ones with a low range of error (Although, I did not check this time). To make the error even less when redoing this lab, you can take the slight resistance in the ammeter and wires into account. One could use the information gained in this lab to develop circuits. If they are trying to set up large multi loop and parallel circuit, they will able to know how the current splits with multiple resistors and branches.
9. Summary of Lesson 4 (Electric Current) on Electric Circuits - Method 4
What are the circuit symbols? Circuit drawings are used to give a quick picture of a circuit for better understanding. The symbols are used to create schematic diagrams.
What are the two types of circuit connections? Circuits can be connected in series, which means that every charge passes through every resistor. When they are connected in parallel, each charge does not have to pass through every resistor. In series, when the number of resistors increases, the current decreases and the resistance increases. In parallel, when the number of resistors increase the current increases and the resistance decreases.
Characteristics of series circuits.
Current in a series circuit is the same everywhere in the circuit. The current through one resistor is the same as a current going through another resistor, or the battery. The equivalent resistance of a circuit is the amount of resistance that a single resistor would need in order to equal the overall affect of the collection of resistors. When two resistors are in a series circuit, you can find the equivalent resistance of those two resistors by just adding up their resistance. The voltage drop of the battery is equal to the sum of the voltage drops of the resistors in the circuit.
Characteristics of parallel circuits.
In a parallel circuit, charge divides up into separate branches. The total amount of current in all the branches when added together is the same as the amount of current at locations outside the branches. The current outside the branches is the same as the sum of the current in the individual branches. The equation for finding equivalent resistance is…
1 / Req = 1 / R1 + 1 / R2 + 1 / R3 + ... For parallel circuits, the voltage drop of the battery is equal to to the voltage drops at every resistor.
Part 1: Basic Electric Circuits
Table of Contents
Hypothesis: Based on previous dealings with batteries to get the light to work it will need a bulb in a socket, battery, and 2 wires connected to battery.
2. What will happen to Bulbs 1 and 2 when you disconnect the wires of the configuration below at the various labeled points?
Hypothesis: At each of the points where the wire is disconnected, lights will not stay on because it is no longer a complete circuit.
Conclusion: Based on the results the lights are not on, the light does not get the electron flow from a closed circuit. This does not allow electrons to flow.
3.What type of object, when inserted into the space labeled “something” in the loop shown below, will allow the bulbs to light?
Hypothesis:
Conclusion: My hypothesis was accurate. All the materials above that did work were metallic, while all those that did not work were, the non metallic materials. The metallic are the conductors and the non metallic are the insulators. The conductors will close the circuit while the insulators do not keep the circuit working.
4. What is a conductor and what is an insulator? How do you know? How can you test this using our loop configuration?
A conductor allows for the flow of electrons, while an insulator does not. I know this because of the last investigation. I made an open circuit, leaving a space open between two wires, one connected to the socket and the other connected to the positive end of the battery. On the negative end, one end of the wire was connected to the battery and the other to the socket. I then connected the two open end of the wires with various objects. Some things were metal while others were not. In the end, the metal objects such as a paper clip and piece of tin foil lighted the bulb.
5. What parts of a socket and bulb are conductors and which are insulators? What is the conducting path through the bulb?
Hypothesis: The clips and the plates on the socket and the threaded section and the tip on the bulb will be conductors. From feel and look they seem to be metal, which is a conductor. Because of the previous data the base on the socket and the black ring and the glass on the bulb will be insulators. The conducting path will run through the fixed metal strips on the blue plastic disc in order for the power to reach the light bulb.
Procedure: Set up a complete circuit, disconnect one wire from the bulb socket. Touch the open wire end to the parts of the socket and see which ones allow the bulb to light. Test out the parts of the bulb.
Conclusion: My hypothesis was accurate. In the socket, the clips and plates were conductors. In the bulb, the threaded section, filament, and tip were conductors and allowed light. Below is the conclusion on the path throughout the bulb and socket.
6. Practice Set: The CCP
Sheet 1
Sheet 2
7. How can you light a bulb using one battery, one bulb, and one wire ONLY? How many different correct ways can you do this? What DIDN’T work, and why?
Hypothesis: To get the bulb to light I will need to touch one end of the wire to one side of the battery and the other to the thread of the bulb while touching the tip to to the positive side of the battery if the negative side is being touched by the other wire. This can be done through two ways.
Conclusion: My hypothesis was pretty correct but there will be four total ways instead of two. Both work with the bulb on positive or negative end instead of just on one. For the bulb to light using the battery, wire, and bulb, both the threaded section and the metal tip must be connected to either the battery or a wire that is connected to the battery. Those two pieces of the light bulb need to be connected to a source of power. There will be no light if either the threaded section or metal tip is not touching a source of power.
8. Practice Set: Basic Circuits
1. in the Following circuit which bulb lights first?
Answer: D they all light the same.
9. What is a circuit?
A circuit is a closed loop of conducting materials that allows electricity to flow freely.
10. What does a compass tell you about what is happening in the wires of the circuit?
Hypothesis: The compass needle will move when the wire is placed directly on top of it.
Procedure:
Data: When wire is placed in same direction of needle, the needle attempts to move perpendicular to the wire.
Conclusion: The needle attempts to move perpendicularly with the electricity flow. The needle will be deflected more with a stronger electricity flow. It deflects in the same direction when touched with the same end of a wire.
11. What effect does reversing the battery pack have on the compass deflection? What does this mean about the role of the battery in the circuit?
Hypothesis: The needle will move in the opposite direction compared to the investigation 10.
Procedure: Set up the same way as previous investigation and switch the two wires connected to the battery and observe what happens.
Data: The needle will move the opposite way compared to the data in investigation 10.
Conclusion: Whichever side the wire is plugged in to defines the path of the electrical flow
12. Practice Set: Wires
2. Explain why you believe your answer to Question #3 is correct. Use the words “insulator” and “conductor” correctly as part of your explanation.
Since the paperclip is a conductor, they both will have the same brightness because the same amount of charge will pass throughout the circuit. If it was an insulator, there would be no light to the bulbs.
3. Write in your own words a definition of the word circuit which anyone could use to determine if a given set of connections is or is not a circuit.
It is a closed loop of conducting objects. They allow a current to flow through.
4. We have observed in several activities that as soon as a very small gap is produced anywhere in the circuit, the bulbs go out. Would you classify air as a conductor or an insulator? Explain.
Air is an insulator because electric charges cannot be moved through it. In the cases of high voltage like lightning, air can act as a conductor.
5. Indicate whether each of the following statements is True or False. Then state evidence which either supports or contradicts each statement.
False [a] Charge moves out of each end of the battery into the loop.
Evidence: A compass needle deflects the same way no matter where it is in a loop.
True [b] Light bulbs are non-directional devices. (Whichever way they are connected in the circuit, they behave the same way if you turn them around.)
Evidence: Whatever way a bulb is connected to a circuit, it will have the same reaction. There is a continuous conducting path within the circuit.
True [c] The battery determines the direction of flow of charge in a circuit.
Evidence: The compass needle deflects the opposite way.
False [d] A compass can be used to determine the exact direction that charge flows in a circuit.
Evidence: We do not know the exact direction the charge flows, but the scientific community accepts that it flows from positive to negative.
True [e] Metal substances are generally conductors.
Evidence: Determined from previous investigations placing a metallic substance in the circuit keeps the light lit which means it is a conductor, so they complete the circuit.
13. What is a Genecon and how does it work? What does it tell you about the role of the battery in the circuit and why?
Hypothesis: A Genecon is power source which will effectively take the place of the battery in the circuit.
When cranked connected to a bulb, at a certain speed the bulb, lights.
The crank begins to turn when plugged into the battery. The circuit is completed when the power runs through the motor of the Genecon.
Conclusion: A Genecon is a manual-powered generator. The crank initiates the power, energy is transferred to the gears which move the motor. The power transferred into the motor then transfers electricity to the wires.
14. Readings
15. What is a schematic diagram? What are the symbols for the various circuit elements?
Schematic diagrams represent the components of a circuit through symbols. Schematic diagrams are an easier, more clear way to represent real-life circuits.
16. Practice Set: Schematics
17. Readings: Capacitance
18. What is a capacitor and how is it made?
A capacitor is a three layer device that is used to store certain amounts of charge and energy. It is made by putting an insulator layer (dielectric layer) in between two conducting layers (plates). These layers are rolled up and put inside a cylinder. The plates are made very thin and each has a screw or wire called a terminal, attached to it so it can be connected to a circuit.
19. What is the effect of a capacitor on a closed loop?
Hypothesis: Circuit A will not light unless there is charge already stored in the capacitor. Circuit B will light once the wire are reset, which occurs when they touch each other after being connected to the circuit.
Procedure:
Conclusion: A capacitor is a device used to store energy though a connection to a power source. They eventually stop flow of charge.
20. What is origin of mobile charge? From where does the mobile charge originate during the charging and discharging process?
Hypothesis: Charging circuit- the mobile charge will originate from the batteries. Discharging circuit- the mobile charge will originate from the charge stored in the capacitor.
Procedure: Set up a circuit like the ones below. Which are represented by symbols from schematics, so you need three batteries, a capacitor, and two bulbs with sockets.
Conclusion: Mobile charge originates from where the circuit begins its positive charge that flow.During the charging process, mobile charge originates front the conductors in the circuit. The charges are pushed by the battery to the first terminal. During the discharging process, mobile charge comes from the built- up positive charge in one terminal. The charge then repels the positive charge in the other terminal and pushes it through the circuit.
21. Practice Set: Electrical Energy
22. Make a model: Air Capacitor
23. Investigating the Air Capacitor
24. Practice Set: Capacitance
Part 2: Resistance
1. What effect does the type of bulb have on a capacitor during charging and discharging?Hypothesis: Discharging through the long bulbs will take longer for the long bulbs to go out compared to the round bulbs because of the long's thinner filament. As for the genecon, during the discharge process, the built up charge in the capacitor will cause the genecon to crank because the charge will be running through it.
Procedure:
Conclusion:
Upon switching off between the long bulbs and the round bulbs during the discharge process after charging with the round, I was able to see that the long bulbs stayed on for a longer amount of time in comparison to the round which lastly a bit shorter. During the discharging process of the capacitor, when connected with a genecon, it will cause the genecon's handle to twist in counterclockwise direction. Showing the charge moving away from the capacitor.
2. What are the differences between the filaments of round and long bulbs? (Use a microscope.)
The Filament of the round bulb is thicker and smaller in relation to a long bulb, whereas the filament of the long bulb is thinner and longer.
3. How is air moving through straws analogous to charge moving through a filament?
Air moving through straws is analogous to charge moving through a filament. Breathing through a thick straw is easier and quicker in comparison to a thin straw, which takes longer and is more difficult to breath through. This analogy fits well because it very similar to how charge moves through filaments. With a thin filament, there is a longer time for charge to pass throughout compared to a thicker one. In the thick one, it the charge moves through quicker. Shorter straws were easier to breathe through compared the longer ones. Charge takes longer moving through a longer filament compared to a shorter filament.
4. What is the difference between flow rate and flow speed?
Flow rate is current and how many charges per second. Flow speed is the amount of distance you cover in an amount of time.
5. How does the number of bulbs in a single loop affect the overall current and resistance in a circuit?
Hypothesis: As the number of bulbs increase, the amount of resistance increase, which will slow down current. This will cause the brightness of the bulbs to decrease as the amount of bulbs increase.
Procedure:
Data:
Conclusion: The more bulbs there are the higher the resistance, so the brightness ultimately decreased as more bulbs were added to the circuit. Also, the amount of deflection in the compass also decreased because the current had decreased. That is the charge passing over a given point per amount of time. So, as the the resistance is increased the current will decrease because the charge is moving slower throughout the circuit.
6. Problem Set: Resistance
8. Reading and Questions: Pressure Difference
9. and 10. Color Coding Notes, Activity and Practice Set
11. How does the number of bulbs side-by-side affect the overall current and resistance in a circuit?
Hypothesis: Adding light bulbs will not affect the overall current or resistance. There will be an equal amount of charge flowing through each bulb after the current reaches the junction.
Procedure:
Data:
Conclusion: The number of bulbs in a side by side does not affect the current in these circuits. I was able to se this because the compass deflected the same amount throughout each set up. Resistance stayed the same throughout each circuit. It does not lower the resistance, exemplified by the fact the bulbs were the same brightness. When there are parallel wires all the bulbs light the same.
12. Does adding wires in series or in parallel effect the overall resistance of the circuit?
Hypothesis: Adding wires into a series will not affect the overall resistance because the wires have very little to no resistance. Adding wire in parallel will decrease the overall resistance in a circuit, because it will create a path of less resistance for the charge, essentially one that is easier to move through.
Procedure:
Data:
Conclusion: Adding a wire in series does not affect the overall resistance of the circuit. This is because the wires used nearly have no resistance. When wires are placed parallel into a circuit, it will affect the overall resistance, decreasing it. Since charge wants to move through the path that is least resistant, the one bulb in the circuit will be short-circuited because it is easier for the charge to move through wire than through the bulb. Evidenced by deflection of the compass, as the current increased total resistance decreased.
13. What effect do dueling battery packs have on bulb lighting and flow rate?
Hypothesis: Dueling battery packs will have resistance within a series facing opposite directions but combined voltage when facing the same, but no effect when parallel.
Procedure:
Data:
Conclusion: Adding batteries in a series will add or subtract from the total charge moving throughout the circuit. This is because the batteries themselves have resistance within the circuit.
14. Practice Set: Battery Structure
15. How does mixing bulbs in series affect flow rate and pressure in each part of the circuit?
Hypothesis: Mixing Bulbs in a series will affect the flow rate making the circuit flow at the resistance of the most resistant light bulb which is the long bulb. The long bulb will light while the round bulb will not. When the capacitor is added, the long bulb will not light at first and the round bulb will be lit but as the resistor builds resistance, the round bulb will begin to go out while the long bulb's brightness will increase.
Procedure:
Conclusion: Mixing bulbs in a series will cause a change in the flow rate and the resistance throughout the circuit. The flow rate depends directly on the most resistant object in the circuit. The circuit will flow at the rate of the long bulb so the round bulb is not lit. When a capacitor is added, it short circuits the long bulb when it begins to charge. The round bulb will be lit brightly because the long bulb is short-circuited but as the capacitor gains charge the long bulb will gain brightness as the round bulb loses brightness.
16. Reading: Mixing Bulbs
Immediately after connection:
Mid-way through the process:
Steady State:
17. What is the effect of adding another round bulb in parallel?
Hypothesis: Adding another bulb in parallel will increase flow rate and cause the bulbs in the series to get brighter.
Procedure:
Data: When the additional bulb is added, the bulbs in a series get brighter, while the parallel bulbs have the same brightness and do not change from what it was previously.
Conclusion: When adding another round bulb in parallel, the flow rate increases. The parallel bulbs let the charge flow through two different paths, which decreases the resistance of the circuit. This results in the two outer bulbs getting brighter and the two parallel bulbs getting dimmer. The two bulbs in series get brighter because the current increases. The two parallel bulbs do not get brighter because the current splits when it is going to the two bulbs.
18. How does the addition of another branch affect flow rate and pressure in the wires?
Hypothesis: By adding another round bulb parallel it will increase flow rate. (we can see this with a compass deflecting more) Circuit 3 will have the highest flow rate and thus the most deflection on the compass. This is because the long bulb shorts out by the parallel wire. The circuit will have low resistance because the highest resistance will be the round bulb which has low resistance.
Procedure:
Data: The compass deflects more when there is less resistance in the circuit. The compass deflected the most when a wire was added. Then when the round bulb was added it deflected a little bit less. Finally when the long bulb was added, the deflection on the compass was the least. With less resistance, the bulbs became brighter.
Conclusion: Adding another branch increases the flow rate because of the amount of compass deflection in the three circuits. For circuit 1 and 2, the pressure was the same. In circuit 3, the pressure increased because the parallel wire shorts the long bulb. Because another option for the charge to flow through is added, the current will increase.
19. What is the effect of decreasing the resistance of right side of the circuit on: a) the flow rate through the battery; b) the pressure difference across the battery; c) brightness of the left bulb
Hypothesis: By adding round bulbs to the right of the circuit, the flow rate will increase. The pressure difference will not be affected so the long bulb on the left will keep a consistent brightness.
Procedure:
Data:
Conclusion: Upon decreasing the resistance of the circuit, it will increase flow rate through the battery, and keep the pressure difference and brightness of the left bulb constant. The flow rate increases because less resistance is added to the right, which is shown through the increased deflection in the compass. The pressure difference remains constant. The long bulb has the same brightness because the pressure difference remains constant and it is not affected by the addition of a parallel branch to the battery.
20. Practice Set: What determines Pressure in the Wires?
21. Activity/ Lab Ammeter Voltmeter
Objective: How do different bulb combinations and arrangements affect the quantitative and Voltage and Current Readings?Procedure: Set Up each of circuits below, and measure pressure difference with a voltmeter and flow rate with an ammeter.
Hypothesis:
A. Predict the bulb brightness and flow rate, showing this with starbursts and arrow tails.
B. Rank each of the circuits in terms of flow rate through the battery
(Least to Greatest) H, G, B, F, D, C, A, E
Data:
Pressure Difference Units are V
Flow Rate Units are A for circuits A, E, and H and milliA for B, C, D, F, and G
When bulbs are in parallel, the voltage throughout the circuit remains constant. The current splits after the junction and add up to the total current at points A and D which are right before and after the battery.
When bulbs are in series, the total voltage throughout the circuit adds up to the voltage in a battery. The current remains the same throughout the circuit in a series.
Discussion Questions:
Conclusion: Quantitatively current and voltage have different readings when working with circuits and in parallel and in series. In parallel, the voltage will all be equal. The currents will add up to the total current of the power source. In a series the currents will all be equal. The voltage will add up to the total voltage of the power source.
22. True/ False Statements
Part 3: Quantitative Analysis of Electrical Circuits
2. Summary of Lesson 2 (Electric Current) on Electric Circuits - Method 4
What is an electric current?Electric current is a flow of electric charge. It is moving electrons in a conductor. Charge moves from an area of high potential to low potential.
What are the requirements of a circuit?
Must be a closed loop. Must have an energy supplies with high and low potential ends. Must consist of all conducting materials
How do you measure electric current?
As a physical quantity, current is the rate at which charge flows past a point on a circuit. Current is I, and is equal to the quantity charge that passes through a point per amount of time. Current is measured using amperes, which is 1 coulomb / 1 second
What is power (in electrical terms)?
Power is the rate at which electrical energy is supplied to a circuit or consumed by a load. A cell does work upon a charge to move it from the negative to the positive side of itself. The work done on the charge is equivalent to the electrical potential energy change on the charge. The electrical power is the rate at which work is done. Power is defined as such: Power is measured using watts, which is joules per second.
What is a common misconception regarding electric circuits?
Batteries are not rechargeable. They die when they lose a significant potential difference between their two terminals.
Circuit need to be completely closed in order to actually have a current. This leads to electric charges flowing throughout the circuit, with the battery supplying the power for the whole circuit. People have misconceptions about how this works, in reality, battery just allows the difference in voltage to start the flows and wear out when the voltage dwindles from resistance.
4. Read and Summarize Lesson 3
What is the journey of a typical electron?Electrons carry charge. It will move from high potential to low. It collides with many atoms of the conducting wire, which causes a loss of energy
What is resistance?
Resistance lessens the flow of charge. Flow rate is the result of how much resistance is present. The longer the wire the more resistance there is. Materials of the conductor affect resistance as well.
What is Ohm's Law?
The equation of Ohm's Law is V=IR. This can calculate current, voltage, and resistance of parts of a circuit. There are such things known as Ohmic material which means that it follows this equation. Non-Ohmic material doesn't follow this equation and has a resistance that is constantly changing depending on the situation.
How does Power fit in with Electrical Resistance?
Electrical power is the rate at which electrical energy is supplied to a circuit or consumed by a load. The equation for calculating power is P=VI. P=RI2 and P=V2/R.
6. Ohm's Law Lab
10/28/11Purpose: We are trying to find the relationship between pressure difference and flow rate. We are also trying to find the difference between ohmic and non-ohmic materials.
Hypothesis: The relationship between potential difference and current is direct with constant resistance because when increasing voltage by adding batteries to a circuit, the bulbs became brighter showing an increase in current. (known from previous investigations)
Procedure:
Materials- variable power supply, batteries/ holders, long bulb and socket, assorted resistors, multimeters, lead wires
1. Set up the above circuit.
2. For the resistor, use 4 different resistors, two different normal resistors, a long bulb, and round bulb.
3. Change the voltage of the circuit at least 5 times when each resistor is completing the circuit. Use the ammeter to determine the current.
4. Record both the voltage and current in excel for each different voltage and resistor.
Data:
Calculations:
Resistance Calculation:
Percent Error Calculation:
Percent Difference Calculation:
Graphs:
Analysis: We started the graphs at 0,0 because when there is no electric potential there is no current. The two resistors we used had linear tread lines. This shows that they follow ohm's law, so they are ohmic resistors.The slope of the line is equal to the electric potential divided by the current. The slope is the resistance, known from Ohm's law where v/i=r. The slope should be equal to the experimental resistance. The tread lines for the round and long bulbs were polynomial (supposed to be power but did not work on our excel sheet). This shows that they were non ohmic resistors. We are able to determine that these tread lines were correct fits for each particular data set because they all had strong R^2 values which determine the fit and accuracy of the line.
Discussion Questions:
Conclusion:
My hypothesis that there is a direct relationship between electric potential and current was correct. We were able to see this graphically upon graphing the data that we recorded from our procedure. On the graphs, as the x value increase, the y value increases, showing a direct relationship. Since we were looking for a direct relationship, we know that when current increases, the electric potential must increase also, so quantitatively we are able to see that this proven true. In our data, the current is at .0128 A when the electric pressure is at .200V, so when the current increases to .0223 A we see that there is an increase in electric pressure to .400V. Looking at the graphs we can determine difference between ohmic and non-ohmic materials. The resistors tread lines that were linear, compared to the bulbs had tread lines, which were power fits. The linear fit equation is the equation from Ohm’s law where v/i= R. The power fit shows there is an exponential relationship on the tread lines of the bulbs, which have determined that they are non-ohmic. They do not follow Ohm’s law because the x value is squared.
Our error was pretty high in compared to our results because our predicted error on the resistors was 5% with a predicted resistance of 22 ohms and 150 ohms. Our experimental error was around 15%, which is much more, then what we had expected. The average resistances we had were 18.18 ohms and 123.76 ohms. Our long bulb and round bulb results had high percent errors at 60 % with an average of 13.7 ohms instead of 60 ohms for the long and 50% with an average 4.69 ohms instead of 10 ohms for the round. This should have been much less, closer to 5-10%. There is a possible error within the bulbs and resistors because they have been used a lot previously. They could have experienced a lot of work and were not as fresh as new bulbs would have been. So to fix it, we should use brand new bulbs and resistors next time. Also there could have been a problem with the manufacturing. Since the bulbs are mass-produced there could have been a problem from the get go. Once again we should just use brand new bulbs.
There are real-life applications within this lab, which can be applied to circuit boards and electronics. It can help to use a resistor to prevent too much voltage flowing through the circuit. The resistor can prevent too much current in the circuit also.
Lab: Kirchoff's Rules 11/3/11
Purpose: We are looking to see how current splits in multi-loop circuits.Hypothesis: The sum of the current in the branches will equal the current of the power supply because current splits in parallel circuits. The most current will flow through the path of least resistance, because as we have investigated charge wants to flow through the least resistant parts of a circuit.
Procedure:
Materials: Resistors, Wire Leads, D- cell batteries, Several digital mutimeters (DMM), 2 power supplies, 3-4 resistors, connecting wires
1. Set Up the following 4 circuits
A
B
C
D
2. Draw a schematic diagram for each.
3. Measure current and voltage in all resistors using an ammeter and voltmeter. (Use as Experimental Values)
4. Calculate current and voltage in all resistors. Use as Theoretical value and calculate the percent error compared to the experimental
Data (experimental):
Circuit A:
Circuit B:
Circuit C:
Circuit D:
Sample Calculations:
Circuit A
Circuit B
Circuit C
Circuit D
Analysis: (The percent error for I, V, andR is highlighted in yellow at the far right of the table)
Discussion Questions:
Conclusion:
My hypothesis was correct. When current splits it they will add up to the current flowing out of the battery and the most current will flow through the path of least resistance. From our data and calculations we can see in circuit C where there is .0096A flowing out of the battery. The circuits of each branch are .0006A, .0080A, and .0010A. When all are adding up they equal the total flow out of the main battery. An example of the most current flowing the branch will the least resistance will be circuit B. where resistor 1 had a resistance of 500 ohms in one branch, and resistor 2 in branch 2 has 1000 ohms. Resistor 1 has .00078A of current and Resistor 2 has .00063A. Since Resistor 1 has less resistance, it has the most current.
Our results of this lab were pretty good demonstrated by the fact we did not have a lot of error. Our error was around the 5% error for most of the current and voltage, but there was an outlier. Resistor 1 in Circuit D had a 15.66% error for I and 23.5% error for V. Although it was not a large amount of error it still can be attributed to the fact we did not take in account the amount of resistance from the ammeter and wires. If we had taken those into account the error could have been slightly lower. Since the resistors resistances are not exact, they could have been the problem. Depending on which one being used, some contain error ranging from 5-20%. Because of this we could have had a resistor with a not so exact resistance, which we did not incorporate into our calculations.
In the future, I would make sure to check the resistors and see their range and try to use ones with a low range of error (Although, I did not check this time). To make the error even less when redoing this lab, you can take the slight resistance in the ammeter and wires into account. One could use the information gained in this lab to develop circuits. If they are trying to set up large multi loop and parallel circuit, they will able to know how the current splits with multiple resistors and branches.
9. Summary of Lesson 4 (Electric Current) on Electric Circuits - Method 4
What are the circuit symbols?Circuit drawings are used to give a quick picture of a circuit for better understanding. The symbols are used to create schematic diagrams.
What are the two types of circuit connections?
Circuits can be connected in series, which means that every charge passes through every resistor. When they are connected in parallel, each charge does not have to pass through every resistor. In series, when the number of resistors increases, the current decreases and the resistance increases. In parallel, when the number of resistors increase the current increases and the resistance decreases.
Characteristics of series circuits.
Current in a series circuit is the same everywhere in the circuit. The current through one resistor is the same as a current going through another resistor, or the battery. The equivalent resistance of a circuit is the amount of resistance that a single resistor would need in order to equal the overall affect of the collection of resistors. When two resistors are in a series circuit, you can find the equivalent resistance of those two resistors by just adding up their resistance. The voltage drop of the battery is equal to the sum of the voltage drops of the resistors in the circuit.
Characteristics of parallel circuits.
In a parallel circuit, charge divides up into separate branches. The total amount of current in all the branches when added together is the same as the amount of current at locations outside the branches. The current outside the branches is the same as the sum of the current in the individual branches. The equation for finding equivalent resistance is…
1 / Req = 1 / R1 + 1 / R2 + 1 / R3 + ... For parallel circuits, the voltage drop of the battery is equal to to the voltage drops at every resistor.